1. Field of the Invention
The present invention relates to a fixed pattern noise removal circuit, a fixed pattern noise removal method, a program, and an image pickup apparatus suitably used for an image pickup apparatus including a complementary metal oxide semiconductor (CMOS) image sensor.
In particular, the present invention relates to a fixed pattern noise removal circuit, a fixed pattern noise removal method, a program, and an image pickup apparatus that remove vertical streak fixed pattern noise from an output signal of an image sensor having an output system for each of a predetermined number of columns. The fixed pattern noise removal circuit effectively removes vertical streak fixed pattern noise by removing fixed pattern noise from an output signal of an image sensor on the basis of a correction signal corresponding to a light-intensity-dependent component as well as an offset component of fixed pattern noise generated by the output system.
2. Description of the Related Art
Solid-state image pickup apparatuses including a CMOS image sensor are well known. A CMOS image sensor is an image pickup element having a photoelectric transducer and a readout circuit disposed on each of pixels thereof. The pixels are randomly accessed, and signals can be read out from the pixels at high speed. In addition, since the CMOS image sensor is produced using a CMOS process, a signal processing circuit including an amplifier and an A/D converter can be easily integrated into one.
One type of CMOS image sensor is a column-based CMOS image sensor that has an output system (a column signal processing circuit), such as an amplifier and an A/D converter, for each of pixels thereof. In a column-based CMOS image sensor, although the pixels are uniformly exposed to light, the outputs of the pixels are non-uniform from column to column due to the variation in the processing properties of the output systems of the columns. Accordingly, column-based CMOS image sensors exhibit vertical streak fixed pattern noise, thereby degrading the quality of an image.
For example, Japanese Unexamined Patent Application Publication No. 2006-135423 describes technology for removing or reducing such vertical streak fixed pattern noise.